The standard and well-known procedure for using an automatic brewing device such as "Mr. Coffee", starts with loading coffee particles on a filter, i.e., a volume of coffee particles commensurate with the volume or number of cups of coffee to be brewed. The filter with coffee particles is then placed in a brewing chamber of the coffee maker where hot water gradually flows through the filter over a period of time and the brewing process takes place. The "Mr. Coffee" filter holder incorporates a ribbed section below and alongside an adjustable control wall which retains the filter. The ribs serve as channels for water which surmounts the control wall to bypass the filter. These channels formed by the ribs serve to direct water to an opening in the bottom of the brewing chamber. As such, the ribs in the "Mr. Coffee" system are not dedicated to controlling hot water-beverage particle contact time; and, the ribs may not adequately serve to aid in controlling hot water flow time and strength of the beverage produced. Finally, the brewed coffee emanates from the brewing chamber by gravity and pours into a carafe seated on a heating element to maintain the hot temperature of the brewed coffee. But the coffee thus produced is generally uniform; i.e., all coffee brewed from successive brew cycles will have the same relative strength.
U.S. Pat. No. 4,056,050 to Brown presents a somewhat complicated means for controlling contact or brew time, wherein a selector cap with a plurality of slots in its sidewalls is rotatively coupled with a spreader, likewise having bypass slots grooved in its control wall, and the selector cap and spreader are both rotatably mounted on a bypass tube, so that when the selector cap and spreader slots are in registration, a relatively greater degree of water enters the brew chamber; and, when the selector cap is rotated to a weaker brew position, some of the corresponding slots move away from position of registry and a lesser amount of heated water enters the spreader as greater amount of water bypasses the brewing chamber through the bypass tube. Thus, water bypass for contact time and brew control is somewhat complex and is accomplished by means of the registration of a plurality of corresponding slots.
In our U.S. Pat. No. 4,446,158, there is disclosed an apparatus for making individual beverage quantities including a disposable coffee container and filter unit. Since the degree of extraction from the precursor particles is a function of the time during which hot water contacts the particles in the coffee making process, U.S. Pat. No. '158 incorporates a bypass slot or recess to allow added control for the rate of water flow through or by the coffee filter unit. The bypass simply provides a path for water not necessary to complete efficient extraction and, therefore, comprises a means to control time in a manner that is independent of the flow resistances through the filter unit. Changes in the size of the bypass slot or recess can obviously be used to control the time of the coffee making cycle and thereby control strength of the brewed beverage product. However, the apparatus for brewing disclosed in U.S. Pat. No. '158 does not incorporate a means for varying size of the bypass slot to control strength of the brewed beverage. Since the apparatus is not adapted to change size of the bypass slot, the bypass rate cannot be varied. Therefore, each unit produces a brewed beverage of uniform strength like any other brewing device or a "Mr. Coffee" in the prior art.
Our U.S. Pat. No. 4,697,502, heretofore obtained, discloses a less complex device having a means for varying size of the bypass slot and hence controlling the brew strength with use of the filter disk disclosed U.S. Pat. Nos. '158. In the '502, an adjustment ring is tapered to have a variable vertical height or wall and the ring is rotatedly carried by a mounting plate. Stated otherwise, the ring rotates relative to the mounting plate. The wall of the ring impinges a bypass slot in a side of the mounting plate for opening and closing the slot as the ring rotates on the mounting plate, thereby controlling volume of heated water bypassing the filter particles and concomitantly controlling hot water-beverage precursor contact time and strength of the brewed beverage.
The design incorporated in the U.S. Pat. No. '502 has been found impractical in many respects, among others, that the stops for opposite ends of rotation for the adjustment ring are positioned on the underside of the mounting plate, which mandates to some extent that the indicators be located on lower surface of the mounting plate. Additionally, the fact that the adjustment ring is rotatedly mounted on the plate requires construction of the apparatus from three or more components which may be found impractical for manufacture and use, not sufficiently sturdy and durable, too expensive and not commercially feasible.
In view of the various drawbacks and deficiencies in the prior art brewing devices, it is a primary object of the present invention to provide a brewing device for preparing a brewed beverage of predetermined strength by regulating hot water-particle contact time, controlling the volume of heated water bypassing filter particles, and thereby control strength of the brewed beverage.